Process of removing carbon from pressed bodies of tungsten.



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To all w am it may concern:

Be it known that I, Dr. Farrz BLAU, chemist, a Subject of the Emperor of Austria-Hungary, and a resident of S. W. 13, Alto J akobstrasse 139, Berlin, Germany, have invented certain new and useful Imrovements in Processes of Removing Car on from Pressed Bodies of Tungsten; and I do hereby declare the following to be a full, clear, and exact descriptiomof the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

My. invention relates to an improved method of producing incandescent bodies for electric incandescent lamps.

I have heretofore employed a method for producing incandescent bodies for electric incandescent lamps from common heat-resisting metals, such as molybdenum, tungsten, vanadium, tantalum, consisting in first producing crude incandescent bodiescontaining carbon-such as one pressed from a powdered metal with the addition of an organic binding materialeand then heating the same in an atmosphere that simultaneously reduces or preserves the metals and oxidizes the carbon, until the metals have been freed from carbon or contain only such a minute residue of carbon as not to'injure the quality of the incandescent body.

The object of the present invention is, while retainin the reducing gases, to replace the oxidizing gases by such gases as remove the carbon, though not in the form of a compound of carbon and oxygen, that isby oxidization, but in another form. As described these reducing gases are adapted to surround and envelop the filament during the heating stage and they are supplied in quantities sufiicient to accomplish the desired object of freeing the metal from carbon or until the filament contains only such 2. minute residue of carbon asnot to injure the quality of the filament.- In order to accomplish this result, it is apparent that the amount of reducing gases employed 'for each filament must be in excess of the quantity theoretically required to remove the total carbon contents of the crude filament.

In. carrying theinvention into efiect, the removal of the carbon isfedected by the use of gases containing no oxygen, and especially Specification of Letters retest.-

1 hydrogen, or

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in-the presence of nitrogen, which is used admixed m large roportion with the reducing etter still in the form of gaseous ammonia. An essential point with reference to the use of these gases (hydrogen, etc.) is that they shall not have any appreciable oxy en constituents so that the oxidation of t e carbon of the crude filament is positivelysavoided and so that this carbon will be removed by a reaction or series of reactions in which oxygen plays no part. in using such a mixture with hydrogen, or ammonla, the carbon is also eliminated, apparently in the form of cyanogen and hydrocyanic acid. This method resents the advantage over the method ascribed in my former a plication'-*in that it can be much more easi y carried out, so that even where there is some amount of carelesshess, there is no danger of the resulting metal filament being attacked by any'excess of added oxidizin gas. This is apparently due to the fact t at the electric dlscharges which occur upon passing the current through the incandescent body when operating in the diluted gases, facilitate theelimination oi the car- The improved method is especially applicable for eliminating carbon from tungsten and molybdenum filaments containing carbon.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States of America, is:

L-The recess of removing carbon constituents rom pressed bodies oi tungsten containing carbon which consists in heating said body in an atmosphere composed essentially of nitro%en and hydro en and in removin g'the car oxidized gaseous form by the agency of the nitro en contained in said atmosphere.

2. he recess of removing carbon constituents rom pressed bodies oi tungsten containing carbon which consists in heating said body in an atmosphere composed essentially of hydrogen gas and a relatively large quantity of nitro on and; in removmgthe carbon from sai body in an unoxid zed gaseous form by the agency of the nitrogen contained in said atmosphere.

'3. The process at removing carbon con= n3, least Ell on from said ody in an un- Q I memee stituents from pressed bodies of tungsten In testimony, that I claim the foregoing as containing carbon which consists in heating my invention, I have signed my name in said body in an atmosphere composed essenpresence of two subscribing witnesses. tially of hydrogen gas and gaseous ammonia, 'DR. FRITZ 'BLA'U.

5 and m removin the carbon from said body Witnesses:

in an unoxidize gaseous form by the agency. HENRY HAsPmz, of the nitrogen contained in said atmosphere. Women HAUPT, 

